off the top of my head
ka p90 (some models)
most ares guns but the spring guide is shit, usually breaks. the g36 has an upgrade guide but the stock locking screw that aligns the guide doesn't thread in so you need to order the screw separately direct from ares.
ics split gearbox is also an option.
Honestly with the price of guns these days, I'd buy a 2nd one and set it up for cqb fps, that way when your field gun breaks, you have a backup.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.